Apparatus for separating clean from refuse chips in the manufacture of wood-pulp.



Patented Feb. 18, I902. T. P. uamzss.

0F woou PULP I (Application filed May 15, 1899.)

APPARATUS FOR SEPARATING CLEAN FROM REFUSE CHIPS IN THE MANUFACTURE (NoModel.)

Patented Feb. I8, 1902.

T. P.. BURGESS. APPARATUS FOR SEPABAIING CLEAN FROM REFUSE CHIPS IN THEMANUFACTURE 0F WOOD PULP. (No Mada) Appiicmon filed May 15, 1899.

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UNlTFD STATES PATENT FFICE.

THEODORE I. BURGESS, OF BERLIN, NEW HAMPSHIRE, ASSIGNOR TO THE BURGESSSULPHITE FIBRE COMPANY, OF BOSTON, MASSACHUSETTS, A

CORPORATION OF MAINE.

APPARATUS FOR SEPARATING CLEAN FROM REFUSE CHIPS IN THE MANUFACTURE OFWOOD-PULP.

SPECIFICATION forming part of Letters Patent No. 693,684, dated February18, 1902 Application filed. May 15, 1899. Serial No. 716,840. (Nomodel.)

To all whom it may concern.-

Be it known that I, THEODORE PHILLIPS BURGESS, of Berlin, in the countyof Coos and State of New Hampshire, have invented a new and usefulApparatus for Separating Clean from Refuse Chips in the Manufacture ofWood-Pulp, of which the following is a specification.

In the manufacture of wood-pulp by the sulfite process the wood is firstreduced to the form of chips, which are treated in digesters; but beforesuch treatment itis highly desirable that the chips best fitted fortreatment shall be separated from those contain- I 5 ing knots or piecesof bark or which are for any reason not desirable in the digester, andsundry forms of apparatus are now known for separating the clear chipsfrom the refuse chips.

My invention relates to separating the clear chips from the refuse chipsand is based upon my discovery that if a layer of chips be floated uponthe surface of the water in a tank and be gently propelled over thatsurface in a horizontal plane and at the same time gently stirred, sothat the floating layer of chips is broken up both in the direction offlow and also in practically all other directions at the same time, theseparation of the refuse chips from the clear chips will be made morecomplete than by any other means known to me.

My theory is that the refuse chips, which are thoroughly mixed with theclear chips, but which constitute only a small part of the bulk of themixed mass of chips, are prevented from sinking by the buoyancy of theclear chips by which they are surrounded and that only those refusechips which happen to be unsupported by neighboring clear chips sink;but whether this be the true theory or not it is a fact that when themixed chips are plunged or forced under the surface of the water many ofthe heavier refuse chips are so sustained by the lighter clear chipsabout them that they float oif together and the separation. is veryimperfect, and it is also a fact that when a layer of mixed chips isfloated on the surface of the water and gently pushed along that surfacein one general direction by frictional propellers, 5o

. which also act to move the chips of the float- Although my newprinciple will be well understood from What has been already said, yet adescription by reference to the drawings of the best modes in which Ihave contemplated applying it is necessary for its full appreciation. o5

In the drawings, Figures 1 and 2 are a plan and elevation illustratingone form of apparatus embodying my invention; Figs. 3 and 4, like viewsof another form of apparatus also embodying my invention, and Figs. 5and 6 like views of a third form of apparatus embodying my invention.

The tank A is as usual and is provided with appropriate means forfeeding the chips B and maintaining the water-level, as usual; but thesurface of the water is occupied by the rubbing-propellers, which may befingers d, staggered, as in Figs. 1, 2, 5, and 6, or spiral blades d, asin Figs. 3 and 4:. These rubbing-propellers move the blanket or layer ofchips B over the surface of the Water in one general direction, but,inaddition, practically each chip is given a motion additional to itsgeneral forward motion with the layer, and the combined motion thusgiven dislodges practically all of the heavier chips from the littlerafts formed by lighter chips. The fingers cl and the blades d are movedby revolving the rolls by which they are carried.

It is evident that as the rollers carrying the arms or teeth (Z arerotated the layer of chips will be broken up in practically alldirections, for the chips which are pushed forward by the teeth (Z willbe moved more rapidly than those which are either behind or on 5 eitherside of them, and they will also usually be thrust aside by the armswith a whirling motion, and at the same. time other chips will becarried forward or laterally into the vortices or eddies caused by thepassage of the arms through the water. Thus it happens that the floatinglayer is thoroughly broken up in all directions. This is also the casewith the chips when they are subjected to the action of the blades d inthe form of device shown in Figs. 3 and 4E. The rollers or shafts uponwhich the propelling-arms (1, Figs. 5 and 6, are mounted do not come incontact with the surface of the water, and the layer of chips istherefore allowed to float at all times upon the surface of the waterand is at no time submerged. In case these rollers were set so thattheir lower surfaces were below the surface of the water the layers ofchips would necessarily be submerged while passing beneath the rollersand the heavier chips and refuse,which are supported by the lighterchips, acting as rafts, would be held tightly against the body of therollers by the buoyancy of the lighter chips. The chips would thereforeall travel at practically the same speedviz. the speed of the roller.The teeth upon the rollers at this time would therefore be ineffectivetoward breaking the heavier chips away from the lighter chips,which buoythem up.

The operation will be plain without detailed description, except thatthe number of frictional propellers and the area of the surface of thewateroccupied by them will vary with the thickness and the rate oftravel of the floating layer of chips.

In practice it is found that the layer of chips should preferably befrom one-quarter to one-half of an inch in thickness and should travelabout fifteen or twenty feet per minute.

What I claim as my invention is-- 1. An apparatus for separating clearchips from refuse chips, comprising a tank of liquid to receive afloating layer of mixedchips, and propellers acting to push the floatinglayer of chips in a horizontal plane over the surface of the liquid inone general direction, the said propellers having theirpropellingsurfaces arranged in a staggered or spiral manner, whereby thechips are moved relatively to one another and the floating layer brokenup in practically all directions.

2. An apparatus for separating clear chips from refuse chips, comprisinga tank of liquid to receive a floatinglayer of mixed chips and astirring device having its body removed from the surface of the liquidand having arms which engage said chips whereby said floating layer ofchips is broken up in practically all directions.

THEODORE P. BURGESS.

WVitnesses:

W. M. HOFFSES, E. H. WILLIAMS.

